Mathias Verraes has followed up his previous post about named constructors in PHP with a bit more clarification about when to use static methods (as he did in his "multiple constructor" examples previously).

Some of the reactions to my last blog post on Named Constructors in PHP, originate from the notion that static methods are inherently bad and should never be used. This is rather overgeneralized. Static methods are nothing more than namespaced global functions. Namespacing, I think we can all agree on, is great. As for global functions: We use those all the time. The native functions in PHP form our basic building blocks.

He talks about the main problem with their use, the shared global state, and compares it to a more stateful service. His solution is to either move to a normal object state (that allows for internal tracking) or think more about abstractions and how they relate.